Michael Tobis wrote: > http://www.nytimes.com/2006/06/27/science/earth/27cool.html > > "In the past few decades, a handful of scientists have come up with > big, futuristic ways to fight global warming: Build sunshades in orbit > to cool the planet.
This is a nutty idea, but it now has urban legend status. The sunshade would have to have an impossibly large area. I made this calculation in another post last year. =-=-=-=-=-=-= Let's run some numbers on this idea . . . The solar constant is ~1367 Watts per Meter squared http://en.wikipedia.org/wiki/Solar_Constant Global Warming is now about 3 watts per meter squared, which is 0.2% of the solar constant. http://www.giss.nasa.gov/data/simodel/ (Global Warming will quadruple in a century or two.) The cross sectional area of the Earth is 125,000,000 km² http://en.wikipedia.org/wiki/Solar_Constant The area of sunshade in orbit needed to remove the current global warming is, therefore roughly .002 * 125,000,000 km squared or 300000 km squared. If your sunshades were one 10,000th of a meter thick and made of Aluminum, you would need to orbit 30 km cubed worth of Aluminum. The density of Aluminum is 2.70 g/cm³. http://en.wikipedia.org/wiki/Aluminum One km cubed is equal to 10 to the 15 cm cubed. So you want to orbit 8 times 10 to the 13 the power kg of Aluminum. Well then, GOOD LUCK. Even if you could reduce this by, say, making your sunshades 1/1000 thiner, it would still be impossible. But . . . I've got an idea! WHY NOT JUST REDUCE THE EMISSIONS OF GREENHOUSE GASES? Wouldn't that be easier? Of course, one could not write good science fiction with this solution, because greenhouse gas reduction is just too practical. -.-. --.- Roger --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
